A condensed version of this article will appear in the 2013 December edition of the Canadian Nuclear Society’s BULLETIN.

The frequent periods of Surplus Baseload Generation (SBG) on Ontario’s electricity system arise when baseload supply exceeds demand. The Independent Electricity System Operator (IESO) takes steps to minimize the amount of SBG when it is forecast by increasing positive price out of province exports, reducing hydro and gas generation to the technical/contractual minimum, and reducing output of the Bruce A/B nuclear stations to the technical minimum by bypassing steam around the turbine-generators. Further reductions in SBG then come from curtailing output from wind generation and finally from nuclear unit shutdown. The major contributor to SBG is the 2,000 or so nameplate MW of unreliable intermittent wind on the system, soon to increase to around 8,500 MW, and not helped by low demand.

Bruce Power now takes output changes in its stride, quickly responding to IESO dispatches day and night to reduce or increase output. Bruce Power should be congratulated for its initiative in providing the IESO with 2,400 MW of nuclear flexibility to help the IESO handle SBG (reference 1), even though it is in relatively large MW chunks. This is not theoretical, the full 2,400 MW amount of curtailment has been provided on occasion. Read the rest of this entry »